The Coen brothers are not the most reliable sources of information about the Coen brothers. Mischievous, and often maddeningly imprecise, they delight in throwing nosy reporters and determined film fans off their trail.

When they were promoting Fargo they insisted the flick was inspired by a real-life murder (it wasn't).

Their introduction to the Big Lebowski screenplay claims the script was a winner of the Bar Kochba Award (which doesn't exist). And when they edit their own movies, they do so under the fake name of Roderick Jaynes.

And now comes A Serious Man, Joel and Ethan's most personal film to date. Many critics have described the movie, which revolves around a Midwestern Jewish professor (Michael Stuhlbarg) - much like their father - as being semi-autobiographical. But during an interview in Toronto with a small group of reporters, the Coens are quick - too quick? - to insist otherwise.

"No, that's not true," says Ethan when asked if the movie's physics professor Larry Gopnik was inspired by their dad, Edward Coen, an economics professor at the University of Minnesota.

"It's semi-autobiographical, I guess you could say, in the sense that the story takes place in a community very much like the one that we grew up in - Minnesota in the 1960s," allows Joel. "But the story is made up and doesn't have anything to do with anything that happened in our family."

In the movie, now playing in area theatres, Larry is beset by more problems than Job. His live-in brother (Richard Kind) won't get off the couch, his wife (Sari Lennick) longs to leave him for a family friend, a student is trying to bribe him for good grades, his daughter (Jessica McManus) talks of nothing but getting a nose job, and his son (Aaron Wolf) is a pot-smoking, F Troop-watching layabout.

"Actually, we were both big F Troop fans," notes Joel. "That part is [autobiographical]."

The Coens grew up in St Louis Park, a mostly Jewish neighbourhood in south Minneapolis, and now live in New York City. While they claim to have never felt the sting of anti-Semitism, the notion of "Jews on the plains" makes the Coens giggle.

"You look at the prairie in Minnesota and you kind of think, or we kind of think - and I don't know why - 'What are we doing there?' It just seems odd," says Joel, 54.

Adds Ethan, 52, "Mel Brooks once had a song called Jews In Outer Space, and I guess that's sort of the idea."

When A Serious Man played the film festival circuit, a minority of critics took exception with some of the portrayals of Jewish characters.

Are the brothers concerned about reaction from the Jewish community?

"I guess one's concern is that a lot of Jews see things through the prism of: 'Is this good for the Jews?'," Ethan says.